1. Field of the Invention
The present invention relates to a measure system for linear planar stepping motor, linear planar stepping motor is used to move work piece, whereas the measure system serves to transmit position signals of the linear planar stepping motor to a control device during the movement of the linear planar stepping motor, so that the linear planar stepping motor will generate with position feedback during movement.
2. Description of the Prior Arts
A conventional linear planar stepping motor is moved at regular pitch by taking advantage of the interactivity between its stator and its mover. The mover is provided with variable magnetic poles, whereas the stator is provided with plural protruded teeth which are spaced by equal pitch intervals. By changing the magnetic poles on the mover, the mover can be driven to move along the stator pitch by pitch.
With the development of the science and technology, a magnetic sensor is additionally provided to linear planar stepping motor for providing precise position feedback. Normally, the magnetic sensor is comprised of protruded teeth and magnetic inductive elements and the sensor itself can produce magnetic field. When the mover is moving, by taking advantage of the variation in air-gap reluctance between the stator and the magnetic sensor, position signals can be measured and transmitted to control device so as to close the control-loop. In this way, a precise position control is obtained.
Since random residual magnetic field will be left on the surface of the respective protruded teeth of the stator after the mover passed (N pole and S pole will be produced alternatively during movement of the mover, and the caused magnetic field will also be varied with the moving speed of the rotor), the magnetic sensor is unable to precisely measure the position of the mover since it will be affected by the residual random magnetic field on the stator when it follows after the mover to move on the stator, as a result, the position control of the control-loop will be inaccurate.
The present invention has arisen to mitigate and/or obviate the afore-described disadvantages of the conventional measure system for linear planar stepping motor.